Synthesis of substituted cyclopentadienes and cyclopentadiene-functionalized polymers

ABSTRACT

Aluminum cyclopentadienyl compounds can be used to synthesize a variety of organic molecules containing the cyclopentadiene group, e.g., substituted cyclopentadiene compounds, polymer molecules with cyclopentadiene pendant groups, and polymer molecules with cyclopentadiene terminal groups.

This is a divisional application of Ser. No. 770,436, filed Feb. 22,1977, now U.S. Pat. No. 4,138,441.

This invention relates to the use of novel aluminum hydrocarboncompounds in the synthesis of substituted cyclopentadienes and polymerscontaining pendant cyclopentadienyl groups and polymers containing aterminal cyclopentadienyl group.

BACKGROUND OF THE INVENTION

It is known that certain hydrocarbon halides such as alkyl halides incombination with organoaluminum compounds initiate the polymerization ofcationically polymerizable monomers, such as isobutylene, styrene,α-methylstyrene, etc. (see for example, U.S. Pat. No. 3,694,377). It isalso known that the hydrocarbon halide need not be a small molecule, butmay be part of a polymer chain, such as exists in chlorobutyl rubber,chlorinated ethylene-propylene copolymer, PVC, neoprene, etc. (see forexample, U.S. Pat. No. 3,904,708).

Comprehensive studies of hydrocarbon halide(initiator)/hydrocarbon-aluminum (coinitiator) initiator systems haveled to an increased understanding of the initiation process (see J. P.Kennedy, J. Org. Chem., Vol. 35 p. 532, 1970). The major conclusiondrawn from these studies is that the aluminum compound interacts withthe hydrocarbon halide to ionize the carbon-halogen bond. The carbeniumion thus generated initiates the polymerization process. The reaction isviewed as proceeding by the following scheme: ##STR1##

Thus the organohalide (RX) reacts with an alkylaluminum compound (R₃'Al) to ionize the carbon-halogen bond in the initiator (eq. 1). In theabsence of monomer (M), the ioncounterion complex collapses via reactionof R⊕ with an anion (R'⊖) from the counterion. However, if monomer ispresent, cationic polymerization ensues and generates amacromolecular-carbenium ion/counterion complex (eq. 3). Subsequently,this complex collapses via alkylation as in eq. 2 to yield a polymerwith R' terminal group (eq. 4).

Knowledge gained from model studies has been exploited in the synthesisof: (1) quartenary-carbon containing compounds via reaction of tertiaryhydrocarbon halides with R₃ Al (see J. P. Kennedy, J. Org. Chem., Vol.35 p. 532, 1970); (2) graft and bigraft copolymers via utilization ofactivechlorine-containing polymers as initiators (see J. P. Kennedy andR. R. Smith, Recent Advances in Polymer Blends, Grafts and Blocks, ed.L. H. Sperling, Plenum Press, New York, 1974, pp. 303-357), and (3)block copolymers via utilization of difunctional initiators (see J. P.Kennedy and E. Melby, J. Macromol. Sci., Chem. A9(5) p. 833, 1975). Itcan thus be seen that exploitation of the hydrocarbon halide/hydrocarbonaluminum reactions has been primarily directed towards a controlledinitiation in carbenium ion polymerizations, and subsequently placingwell defined head groups in polyolefin chains.

Although the model studies also provided an understanding of terminationmechanisms, and showed that termination involved reaction of thecarbenium ion with an anion from the alkyl-aluminum counterion,utilization of the alkylative termination was greatly limited due to theunreactive saturated hydrocarbon groups formed. Outside of synthesis ofquartenary carbon containing compounds, utilization of alkylativetermination has been confined to alkylating active chlorine sites(tertiary or allylic) on PVC. Thus PVC was treated with R₃ Al compoundsto alkylate the active sites, giving the stronger carbon-carbon bonds.It was speculated, and later verified, that such treatment on PVC wouldenhance its thermal stability (see J. P. Kennedy and M. Ichikawa, Poly.Eng. and Sci., 14, p. 322, 1974).

Therefore, the utilization of alkyl halide or hydrocarbonhalide/alkylaluminum or hydrocarbon aluminum reactions to generateorganic compounds with versatile functional groups has been ignored.

The novelty of this invention is a generalized process to synthesizecyclopentadiene-functionalized molecules, and primarily,cyclopentadiene-functionalized polymers, via Lewis acid chemistry. Thescope of functionalized polymers prepared by the processes of thisinvention include polymers with cyclopentadiene pendant groups andpolymers with cyclopentadiene terminal groups.

The prior art in the synthesis of polymers with pendant cyclopentadienegroups involved either copolymerizations with allyl-dicyclopentadienecompounds, with subsequent thermal cracking of the dicyclopentadienependant groups, or by reaction of alkali metal salts of cyclopentadienewith halogenomethylated polyethers (see U.S. Pat. No. 3,826,760). Theseprocesses are limited by the problems inherent in copolymerizations,e.g., blockiness, and the general detrimental effect bases have onchlorine-containing polymers.

The prior art in the synthesis of cyclopentadiene-end group polymersinvolves the capping of living anionic polymerization chains withfulvenes, subsequent reaction with an alcohol yielding polymers withcyclopentadiene terminus (see Japanese Pat. No. 100,492/73). Thereaction was viewed as occurring by the following scheme, illustratedwith butadiene monomer: ##STR2## This process is limited to monomerswhich will polymerize anionically e.g., conjugated dienes, styrene andits derivatives.

SUMMARY OF INVENTION

It has been found that aluminum cyclopentadiene or aluminumcyclopentadienyl compounds R_(x) 'Al(CPD)_(y), as hereinafter defined,can be used as cyclopentadienylating agents in reactions with certainhydrocarbon halides. More specifically, R_(x) 'Al(CPD)_(y) reacts withactive-halogen-containing compounds, such as tertiary, allylic orbenzylic halides, resulting in the replacement of the chlorine with acyclopentadiene group. The active halogen may be attached to a smallmolecule, such as tertiary-butyl chloride or allyl chloride, or attachedto a polymer such as chlorobutyl rubber, chlorinated ethylenepropylenecopolymer or neoprene, which contains small amounts of tertiary -allylicchlorines. It has also been discovered that cationic polymerizationsinitiated with RCl/R_(x) 'Al(CPD)_(y) systems terminate via alkylationof the polymeric carbenium ion with a CPD group from the alkylaluminumhalide counterion.

In brief, the process of this invention involves the mixing of certainhydrocarbon halides or active-halogen-containing polymers with R_(x)'AlCPD_(y) and in some cases with a cationically polymerizable monomerfor polymerizations in bulk or in an inert solvent in the temperaturerange from about -80° C. to +50° C. for periods sufficient to effect thedesired conversions.

DETAILED DESCRIPTION OF INVENTION

In particular this invention relates to the use of aluminumcyclopentadienyl compounds in conjunction with suitable organo halidesin the synthesis of: (1) substituted cyclopentadienes and (2) polymerscontaining cyclopentadiene pendant groups. This invention is furtherdirected towards the employment of hydrocarbon halide/aluminumcyclopentadienyl compound R_(x) 'Al(CPD)_(y) initiator/coinitiatorsystems for the synthesis of cylopentadiene-terminal group polymers.

Still more particularly, this invention relates to the synthesis ofsubstituted cyclopentadienes by reaction of tertiary, allylic orbenzylic halides with R_(x) 'Al(CPD)_(y) compounds;

    RCl+R.sub.x 'Al(CPD).sub.y →R-CPD+R.sub.x 'Al(CPD).sub.y-1 x.

This invention also relates to the modification ofactive-halogen-containing polymers, substituting a cyclopentadiene groupfor the halogen atom, i.e., ##STR3##

These polymer modification reactions offer a unique and novel way ofattaching a very versatile group, the cyclopentadiene group, torelatively non-functional group polymers. The pendant cyclopentadienegroups can undergo a variety of subsequent useful reactions, e.g.,Diels-Alder condensations, including dimerization of the cyclopentadienependant group, yielding thermally reversible crosslinks viaDiels-Alder/retro-Diels-Alder reactions.

This invention is further directed towards the synthesis of polymerswith cyclopentadiene end groups. Thus, a process of this invention canbe employed for the synthesis of reactive end-group polymers viapolymerization of cationically polymerizable monomers initiated withhydrocarbon halide/R_(x) 'Al(CPD)_(y) initiator systems.

    RX+R.sub.x 'Al(CPD).sub.y .sup.nM R--M--.sub.n CPD+R.sub.x 'Al(CPD).sub.y-1 X

The processes of this invention involve the mixing of suitablehydrocarbon halides with aluminum cyclopentadienyl compounds in thepresence of monomer for polymerizations in inert solvents in thetemperature range of -80° to +50° C.

Suitable hydrocarbon halides (RX) are those defined as tertiary, allylicor benzylic. More precisely, suitable alkyl halides are those in whichthe halogens are on tertiary, allylic or benzylic carbon atoms. Thehalogen (X) may be either chlorine, bromine or iodine.

Representative, but not exhaustive, of suitable hydrocarbon halides are:tertiary butyl bromide, tertiary butyl chloride, tri-n-butylchloromethane, allyl chloride, methallyl chloride, crotyl chloride,1-chloro-butene-2, 2,6-dichloro-2,6-dimethylheptane,2-chloro-6-bromo-2,6-dimethylheptane, benzyl chloride, benzyl bromide,methylphenyl chloromethane, triphenyl chloromethane, and the like.

By aluminum cyclopentadienyl compounds is meant compounds of the typeR_(x) 'Al(CPD)_(y), where CPD represents the cyclopentadine group, R'represents an alkyl, cycloalkyl, alkenyl, cycloalkenyl or aromaticgroup, y equals one to two, and x equals two to one, the sum of x and ybeing equal to three.

Representative, but not exhaustive, of suitable coinitiators are:diisobutylaluminum cyclopentadiene ordiisobutyl(cyclopentadienyl)aluminum, diethylaluminum cyclopentadiene ordiethyl(cyclopentadienyl)aluminum, dimethylaluminum cyclopentadiene ordimethyl(cyclopentadienyl)aluminum, methylaluminum-bis-cyclopentadieneor methyl(bis-cyclopentadienyl)aluminum andaluminum-tris-cyclopentadiene or tris-cyclopentadienyl aluminum.

The preferred organoaluminums of the present invention are R₂ 'AlCPDcompounds, and the most preferred is dimethylaluminum cyclopentadine ordimethyl(cyclopentadienyl)aluminum.

Suitable solvents for RX+R_(x) 'Al(CPD)_(y) reactions are those whichwill not deactivate the aluminum compound. Representative, but notexhaustive, of such solvents are aliphatic hydrocarbons, e.g., pentane,hexane, cyclohexane, or chlorinated hydrocarbons, e.g. methyl chloride,ethyl chloride, dichloromethane, 1,2-dichloroethane, chlorobenzene,o-chlorotoluene, and the like.

The ractions can be conveniently carried out in the +50° to -80° C.range, however, the preferred range is +25° to -70° C. and mostpreferably 0° to -50° C.

The synthesis of substituted cyclopentadienes is carried out by mixingRX with R_(x) 'Al(CPD)_(y) preferably in an inert solvent. The additionorder of the components is not critical, however, it is preferred to addRX, as a dilute solution or neat, to a R_(x) 'Al(CPD)_(y) solution.Although the molar ratio of RX to R_(x) 'Al(CPD)_(y) (X/Al) is notcritical, it is preferred to employ X/Al ratios in the range of 0.10 to1.0. Staying within this molar ratio minimizes the formation of RAlX₂compounds, which are thought to lead to detrimental side reactions.

The temperature at which the reactions are carried out is within the+50° to -80° C. range, preferably +20° to -65° C. and most preferably 0°to -55° C.

The reactions of alkyl halides with R_(x) 'Al(CPD)_(y) compounds isviewed as occurring by the following scheme, invoking a carbeniumion/counterion transitory complex. ##STR4## The substitutedcyclopentadiene product can consist of several isomeric products basedon the point of attachment of the alkyl group to the cyclopentadienering. The isomers being 1,2 or 5-alkyl cyclopentadiene, illustratedbelow ##STR5## However, the isomeric product is not critical to thepresent invention.

The synthesis of polymers with cyclopentadiene pendant groups is similarto that employed for the synthesis of substituted cyclopentadienes.However, the alkyl halide in this process is a polymer containing manyactive-halogen sites. Again, by active halogen is meant halogensattached to tertiary, allylic or benzylic carbon atoms. Suitablepolymers which can be cyclopentadiene-functionalized by treatment withR_(x) 'Al(CPD)_(y) compounds include: polyvinylchloride, polyvinylidenechloride, polyvinylbromide, polychloroprene and the like. Still othersuitable examples are polymers which have been modified bypost-polymerization treatment to introduce active halogens onto thepolymer backbone include: chlorobutyl rubber, brominatedbutyl rubber,chlorinated ethylenepropylene (Cl-EPR) copolymer, chlorinated naturalrubber, chlorinated ethylene-propylene-diene (Cl-EPDM), chlorinatedpolyethylene and the like.

It is noted that some of the above polymers are not generally thought ofas containing tertiary, allylic or benzylic halogens, however, suchgroups are frequently introduced into the polymer by an irregularaddition step, e.g., small amounts of 1,2 addition of chloroprene, in anotherwise essentially 1,4 polymerization, results in polychloroprenecontaining small amounts of tertiary-allylic chlorines.

The R_(x) 'Al(CPD)_(y) modification of active-halogen-containingpolymers to yield polymers with cyclopentadiene pendant groups iscarried out by mixing the subject polymer with R_(x) 'Al(CPD)_(y) in aninert solvent. Suitable solvents are the same as described earlier forthe synthesis of substituted cyclopentadienes, however, the solvent nowhas the added qualification that it must be a good solvent for thepolymer also. Although the addition order of components is not critical,it is more convenient to add a R_(x) 'Al(CPD)_(y) solution to thepolymer solution.

The preferred R_(x) 'Al(CPD)_(y) to polymer weight ratio is dependentupon the polymer employed and thus on the amount of polymer-bound-activehalogens, temperature and desired reaction time. However, the best R_(x)'Al(CPD)_(y) to polymer weight ratio can readily be determined by oneskilled in the art.

As in the synthesis of substituted cyclopentadienes, the polymermodification reactions are run in the +50° to -80° C. range. However,the preferred range is +35° to -65° C., and more preferably +20° to -55°C.

The cyclopentadienylation of active-halogen-containing polymers withR_(x) 'Al(CPD)_(y) is viewed as occurring by the following scheme##STR6##

Due to the great propensity for the pendant cyclopentadienes to undergoDiels-Alder dimerization, yielding a cross-link polymer, i.e., ##STR7##the derivatized polymers should be stored at low temperatures. However,it has been found the crosslinks so obtained can be broken by heatingto >150° C., i.e., thermally reversible crosslink, (this work and U.S.Pat. No. 3,826,760). Also, the cyclopentadiene groups can be capped,thus preventing gelation, by reaction with other dienophiles, e.g.maleic anhydride. Indeed, the reaction of the cyclopentadiene groupswith polar dienophiles offer a simple route to attaching polar groups tothe cyclopentadienylated polymers.

The synthesis of polymers with cyclopentadiene terminal groups iscarried out by mixing a suitable alkyl halide (RX), R_(x) 'Al(CPD)_(y)and a cationically polymerizable monomer in an inert solvent. Thepreferred order is to add R_(x) 'Al(CPD)_(y) to the monomer (bulk or insolution), followed by RX under vigorous mixing.

R_(x) 'Al(CPD)_(y), RX and inert solvents are the same as describedearlier. Suitable monomers are those classified as cationicallypolymerizable. Representative, but not exhaustive, of such monomers are:isobutylene, styrene and its derivatives, methylene nobornene,cyclopentadiene, dimethyl butadiene, and piperylene.

It is to be noted that the above list of monomers includescyclopentadiene. It may therefore appear that the cyclopentadiene endgroup would be consumed by cationic polymerization. And indeed, in allthe various cyclopentadiene-functionalized molecules described in thisinvention, it would be expected that cationic reactions would consume alarge portion of the functional group. However, detailed studies haveshown that the kinetic product of the cyclopentadienylations describedherein is the 5-substituted cyclopentadiene (J. P. Kennedy and K. F.Castner, Polymer Preprints, in press), which under the conditionsemployed in this invention is not consumed via side reactions.

The polymerizations can be carried out in the +50° to -100° C. range,however, the preferred range is 0 to -90, and the most preferred rangeis -30° to -80° C.

One of the specific embodiments of this invention is the method ofpreparing polymers containing pendant cyclopentadiene groups whichcomprises reacting a polymer containing pendant active-halogens selectedfrom the group consisting of chlorine, bromine and iodine with analuminum cyclopentadienyl compound of the formula R_(x) 'Al(CPD)_(y)wherein CPD represents the cyclopentadiene group, R' represents analkyl, cycloalkyl, alkenyl, cycloalkenyl, alkaryl or aryl group, yequals 1 to 2 and x equals 2 to 1 and the sum of x plus y is equal to 3.

Another of the embodiments of this invention is a method of preparationof hydrocarbon-substituted cyclopentadienes which comprises reacting acompound of the formula R_(x) 'Al(CPD)_(y) wherein CPD represents thecyclopentadienyl group, R' represents an alkyl, cycloalkyl, alkenyl,cycloalkenyl, alkaryl or aryl group, y equals 1 to 2 and x equals 2 to 1and the sum of x plus y is equal to 3, with a tertiary, allylic orbenzylic halide of the formula RX, wherein R is selected from the groupconsisting of alkyl, cycloalkyl, alkenyl, cycloalkenyl, alkaryl or aryl,and X represents chlorine, bromine or iodine.

Another embodiment of the present invention is a method for preparing apolymer containing a cyclopentadiene terminal group which comprisesreacting a material selected from the group consisting of isobutylene,styrene and α-methylstyrene with an initiator consisting of tertiary,allylic or benzylic halide of the formula RX, wherein R is selected fromthe group consisting of alkyl, cycloalkyl, alkenyl, cycloalkenyl,alkaryl or aryl, and X represents chlorine, bromine or iodine, and R_(x)'Al(CPD)_(y) wherein CPD represents the cyclopentadiene group, R'represents an alkyl, cycloalkyl, alkenyl, cycloalkenyl, alkaryl or arylgroup, y equals 1 to 2 and x equals 2 to 1 and the sum of x plus y isequal to 3.

When isobutylene, styrene and/or α-methylstyrene is polymerized, themole ratio of RX/R_(x) 'Al(CPD)_(y) may range from 0.1/1 to 5.0/1.

This invention is further illustrated by the following examples. Forthese examples all reactions were run in a stainless steel drybox undera dry nitrogen atmosphere. The products obtained in the synthesis ofsubstituted cyclopentadienes were identified by gas chromatographyemploying peak enhancement with authentic samples. Polymer pendant orterminal cyclopentadiene groups were detected and quantitativelymeasured by UV spectroscopy, and further verified by reactions on thecyclopentadiene group.

EXAMPLE 1 Synthesis of tertiary-butyl cyclopentadiene

In runs 1 through 10, five ml. of 0.025 M dimethylaluminumcyclopentadiene (Me₂ AlCPD) in chlorobenzene was dispensed by pipetteinto 20×150 mm test tubes. The tubes were then capped with screw capsfitted with self-sealing gaskets and Teflon® liners. The reaction tubeswere placed in a constant temperature bath. After allowing sufficienttime for the tubes and contents to attain bath temperature, 0.12 Mtert.-butyl chloride solution in chlorobenzene (tBuCl) already at bathtemperature was added by syringe fitted with hypodermic needle. Afterthe desired time, the reactions were quenched by the addition ofnormal-butyl alcohol.

The amounts of t-butyl chloride, the mole ratio of t-BuCl to Me₂ AlCPD,the time of reaction, the temperature employed and the yield oft-butylcyclopentadiene (t-BuCPD) in mole percent is reported in Table 1below.

                  Table I                                                         ______________________________________                                                                                t-BuCPD                                    tBuCl      [t-BuCl]    Time  Temp. Yield                                 Run  (ml. 0.12M)                                                                              [Me.sub.2 AlCPD]                                                                          [Min] [°C.]                                                                        (mole %)                              ______________________________________                                        1    0.25       0.24        30    +1    60                                    2    0.50       0.48        "     "     63                                    3    0.75       0.73        "     "     70                                    4    0.90       0.87        "     "     66                                    5    1.10       1.06        "     "     24                                    6    0.50       0.48        60    +23   50                                    7    "          "           "     +1    63                                    8    "          "           "     -9    75                                    9    "          "           "     -19   72                                    10   "          "           "     -29   84                                    ______________________________________                                    

The results from runs 1 through 5 indicate little effect of thetBuCl/Me₂ AlCPD mole ratio on the yield of tertiary-butylcyclopentadiene(tBuCPD) for ratios less than ˜0.90. However, at tBuCl/Me₂ AlCPD greaterthan ˜0.90 the yield decreases considerably. Runs 6 through 10 show theeffect of temperature on tBuCPD yield. The increasing tBuCPD yield withdecreasing temperature indicates that lower temperatures increase thecyclopentadienylation to methylation ratio, i.e., ##STR8##

EXAMPLE 2 Cyclopentadienylation of Chlorobutyl Rubber

A commercial chlorobutyl rubber of M_(n) 200,000 and containing 1.1 wt %chlorine was purified by three reprecipatations from benzene by addingmethanol to 5% (wt/vol) polymer solutions. The coagulated polymer wasvacuum dried at 50° C. for 72 hr.

5.0 g of the purified polymer was dissolved in 250 ml of driedchlorobenzene. The reaction vessel was placed into a -23° C. bath. Afterallowing sufficient time for the polymer solution to attain bathtemperature 2.84 millimole of Me₂ AlCPD was added as a 0.025 M solutionin chlorobenzene. After 60 min 2 ml. of methanol was added to thesolution to quench the reaction without effecting coagulation of thepolymer. A 25 ml aliquot of the polymer solution was removed by pipetteand coagulated with methanol. The rest of the polymer solution wasfiltered to remove insoluble aluminum residues, then coagulated with a1% 2,6-ditertiary butyl-p-cresol solution in methanol and vacuum driedat 22° C. for 72 hr.

The cresol-free polymer was reprecipitated 3 times from spectro graden-hexane by coagulation with methanol and rapidly dried at 22° underhigh vacuum. UV analysis on dilute polymer solution in n-hexane showedthe polymer to contain 1.1% (wt) cyclopentadiene. This result indicatesthat 55% of the chlorine sites were cyclopentadienylated.

An aliquot (0.25 g) of the 2,6-ditertiary-butyl-p-cresol-treated polymerwas dissolved in 25 ml of chlorobenzene and 0.25 g of maleic anhydridewas added. After 1 hr at room temperature (to ensure completedissolution of polymer and anhydride) the solvent was heated to refluxfor ˜1 hr. The reaction solution was cooled to room temperature and thepolymer coagulated by the addition of methanol. The polymer was purifiedby three reprecipitations from spectro grade carbon tetrachloride (CCl₄)and vacuum dried. Anhydride content of the polymer was determined by IRanalysis in a dilute polymer solution in CCl₄, and was found to be 1.6%(wt), which corresponds to 1.1% cyclopentadiene.

A portion of the cyclopentadienylated polymer (totally soluble) washeated in a curing press at 150° C. for ˜30 min. After this treatmentthe polymer was found to be insoluble. It was believed that thecrosslinks were due to the Diels-Alder dimerization of the pendantcyclopentadiene groups. To verify this, the polymer was reheated at 170°to effect the retro-Diels-Alder reaction. Although the polymer flowed inthe mold cavity it was still insoluble. It therefore appeared that thepolymer could flow at high temperatures, where the dimer would crack,however, upon cooling the dimer reformed. To substantiate this concept,the crosslinked polymer was heated to 200° C. in hexachlorobutadienecontaining maleic anhydride. Therefore, it was visualized that thependant cyclopentadiene monomer would react with maleic anhydride givinga norbornene dicarboxylic anhydride pendant group, and thus have cappedthe cyclopentadiene group. The polymer thus treated, was solubilized andIR analysis showed the presence of the anhydride group.

EXAMPLE 3 Cyclopentadienylation of Chlorinated Ethylene-PropyleneCopolymer

Using a well known technique a commercial ethylene-propylene rubber(EPR) was chlorinated. The EPR was dissolved in benzene and chlorine gaswas bubbled through the solution while the mixture was treated withultra violet light.

The modification of chlorinated ethylene-propylene copolymer (Cl-EPR)was carried in the same manner as that employed for Cl-IIR. The Cl-EPRwas of M_(n) 65,000 and contained 3.0% (wt) chlorine. However, only asmall portion of these chlorines are thought to be active towardsalkylaluminum compounds, as a result of the free radical chlorinationprocess employed.

The procedure was to dissolve 8.7 g of Cl-EPR in 250 ml of chlorobenzeneand then add 2.5 millimole of dimethylaluminum cyclopentadiene ordimethyl(cyclopentadienyl)aluminum. The conditions and results arereported in Table II below.

                  Table II                                                        ______________________________________                                                             Reaction                                                                             Cyclopenta-                                                                            Cl sites substi-                                      Temp.   Time   diene Content                                                                          tuted with CPD                           Run  Cl/Al*  (°C.)                                                                          (min)  (wt %)   (wt %)                                   ______________________________________                                        1    2.9     -23     60     0.31     6                                        2    1.8     -13     "      0.91     17                                       3    0.55    -13     "      1.3      23                                       ______________________________________                                         *chlorine to Me.sub.2 AlCPD mole ratio                                   

The Me₂ AlCPD-treated polymer in Run 1 has 0.31% (wt) cyclopentadiene.Subsequent reaction with maleic anhydride yielded a polymer containing0.47% (wt) anhydride, which corresponds to 0.31% cyclopentadiene. Thelow cyclopentadiene content for Run 1 probably indicates incompletereaction. The thermally reversible crosslinks observed withcyclopentadienylated Cl-IIR were also operative in cyclopentadienylatedCl-EPR.

EXAMPLE 4 Synthesis of Polyisobutylene with Cyclopentadiene End-Group

Polyisobutylene polymerizations were carried out in test tubes employingthe same technique as described for the synthesis of tBuCPD in Example 1except that isobutylene is included in the recipe.

In a typical polymerization, purified isobutylene (and n-pentane in somecases) was added to cooled chlorobenzene solvent

                                      Table III                                   __________________________________________________________________________                                                  Cyclo-                                                                        penta-                          Isobuty-     Chloroben-                       diene                              lene n-pentane                                                                          zene  Temp.                                                                             Me.sub.2 AlCPD                                                                      tBuCl                                                                             Time                                                                              Yield    content                         Run                                                                              (ml) (ml) (ml)  (°C.)                                                                      (mM)  (mM)                                                                              (min)                                                                             (%)                                                                              Mn × 10.sup.-3                                                                (wt %)                          __________________________________________________________________________    1  2.1  4.2  9.5   -41 0.10   0.20                                                                             52   3 13.3  .49                             2  4.2  2.1  "     "   "     "   34   4 28.8  .23                             3  6.3  0    "     "   "     "   16   3 47.1  .14                             4  3.0  0    13    -33 0.10  1.6 52  90       1.25                            5  "    "    "     -27 "     0.8 45  54       0.87                            6  "    "    "     -20 "     0.8 30  58       0.85                            __________________________________________________________________________

Me₂ AlCPD was added, followed by tBuCl. Polymerizations were terminatedby shortstopping and coagulation with methanol. The polymers were vacuumdried at 30° C. for 72 hrs. Cyclopentadiene content was determined by UVanalysis (employed λ_(max) and extinction coefficient for tBuCPD) ofpurified samples (reprecipitated three times from spectro graden-hexane). Representative results are presented in Table III.

Runs 1, 2 and 3 show the effect of monomer concentration on subsequentcyclopentadiene end group concentration. Thus as the initial monomerconcentration increases, the polymer molecular weight increases.Subsequently, the end group concentration decreases, leading to a lowercyclopentadiene content. However, from the Mn (from GPC) andcyclopentadiene concentration, it is calculated that approximately 72%of of the polymer chains from polymerizations at -41° C. contain acyclopentadiene end group.

Runs 4, 5 and 6 show the effect of polymerization temperature onsubsequent cyclopentadiene content. Thus the lower temperatures favortermination by alkylation with the cyclopentadiene group, parallelingthat observed in the synthesis of tBuCPD.

The polymers prepared in a manner such as that of Example 4 and similarto that of Example 4 can be utilized in a variety of ways. For instancetwo or more polymer chains containing a terminal cyclopentadiene groupcan be heated and the cyclopentadiene portions will undergo aDiels-Alder condensation or dimerization and thereby obtain a chainextension.

Polyisobutylene containing terminal cyclopentadiene groups can bereacted with maleic anhydride in a Diels-Alder condensation to givepolymers containing norbornene dicarboxylic anhydride end groups.Polymers containing such end groups could be employed in a variety ofreactions such as macromer in polyester synthesis or such polymers couldbe condensed with cellulose via the reaction of the hydroxyl groups ofthe cellulose with the anhydride group of the polyisobutylene.

Graft polymers may be prepared by reacting the polyisobutylenescontaining terminal cyclopentadiene groups with polymers containingpendant cyclopentadiene groups such as those prepared in accordance withthis invention to obtain polymers containing polyisobutylene pendantside chains. For instance, a polymer prepared from chlorinated butylcould be reacted in accordance with the present invention, producepolymers containing pendant cyclopentadiene groups and such polymerscould be reacted with polyisobutylene containing terminalcyclopentadiene groups thereby forming a graft polymer havingpolyisobutylene grafted onto a polyisobutylene/isoprene backbone. Inaddition to these high polymer applications, liquid polyisobutylenecontaining a terminal cyclopentadienyl group can also be used inadhesives, viscosity index improvers and motor oil additives.

Therefore, one embodiment of this invention are compositions comprisingpolyisobutylene containing a terminal cyclopentadienyl group of theformula: ##STR9## wherein n ranges from about 25 to about 25,000 and CPDis cyclopentadiene. Another set of interesting polymers would be thosein which the degree of polymerization indicated by n in the formulaabove would range from about 90 to about 18,000. Still other interestingpolyisobutylene containing terminal cyclopentadienyl groups in which thepolyisobutylene degree of polymerization ranges from about 260 to about2600.

While certain representative embodiments and details have been shown forthe purpose of illustrating the invention it will be apparent to thoseskilled in this art that various changes and modifications may be madetherein without departing from the spirit or scope of the invention.

What is claimed is:
 1. A method for preparing a polymer containing acyclopentadiene terminal group which comprises reacting a materialselected from the group consisting of isobutylene, styrene andα-methylstyrene with an initiator consisting of tertiary, allylic orbenzylic halide of the formula RX, wherein R is selected from the groupconsisting of alkyl, cycloalkyl, alkenyl, cycloalkenyl, alkaryl or aryl,and X represents chlorine, bromine or iodine, and R_(x) 'Al(CPD)_(y)wherein CPD represents the cyclopentadiene group, R' represents analkyl, cycloalkyl, alkenyl, cycloalkenyl, alkaryl or aryl group, yequals 1 to 2 and x equals 2 to 1 and the sum of x plus y is equal to 3.2. A method according to claim 1 in which the RX/R_(x) 'Al(CPD)_(y) moleratio ranges from 0.1/1 to 5.0/1.
 3. A method according to claim 2 inwhich RX is tertiary butyl chloride and R_(x) 'Al(CPD)_(y) is dimethylaluminum cyclopentadiene or dimethyl(cyclopentadienyl)aluminum.
 4. Amethod according to claim 3 in which the monomer is isobutylene.